Method for improving light transmittance of microcrystalline glass and terminal

Abstract

The application discloses a method and a terminal for improving light transmittance of microcrystalline glass, and belongs to the technical field of microcrystalline glass. In the scheme, a molten sodium-aluminum-silicon oxide mixture is added into a common chemical strengthening salt bath, the sodium-aluminum-silicon oxide reacts with microcrystalline phases and glass phases on the surface layer of the microcrystalline glass, the proportion of the glass phases and the microcrystalline phases is changed, a refractive index gradient layer is formed from the outside to the inside on the glass surface, light reflection is reduced through light interference, meanwhile, ion exchange is generated between the microcrystalline glass and the salt bath, a stress layer is generated on the surface of the microcrystalline glass, the light transmittance is effectively improved while the strength of the glass is improved, and the chemical strengthening is carried out in a strengthening furnace, so that, compared with vacuum environment coating, the yield of products is higher.

Description

Technical Field

[0001] This invention relates to the field of glass-ceramic technology, and more particularly to a method and terminal for improving the light transmittance of glass-ceramic. Background Technology

[0002] Microcrystalline glass combines the high transmittance and chemical stability of glass with the high strength and thermal stability of ceramics. Therefore, it is widely used in various fields, such as touch displays, electro-optics, astronomical telescopes, bio-microcrystals, and architectural decoration. Different applications have different requirements for the light transmittance of microcrystalline glass; for example, mobile phone camera lenses require a light transmittance of over 97%.

[0003] In existing technologies, there are two main ways to improve the light transmittance of glass-ceramics:

[0004] (1) A film layer is applied to the surface of a glass-ceramic substrate by spraying, sputtering, or vapor deposition. Single-sided coating achieves a light transmittance of 94%, while double-sided coating achieves 97%. Applying the film layer involves creating a film on the surface of the glass-ceramic, which requires a vacuum environment. Dust particles adsorbing onto the glass during the coating process can lead to film loss, resulting in low efficiency and yield. Actual testing shows that the product yield is approximately 65% ​​with this coating method, and single-sided coating takes approximately 90 minutes, while double-sided coating takes approximately 180 minutes.

[0005] (2) By adjusting the composition and proportion of the glass-ceramic components and combining chemical strengthening methods, the strength of the glass-ceramic can be improved while the light transmittance is increased through ion exchange. This method has a significant effect on improving the strength of the glass-ceramic, but relying solely on ion exchange has limited effect on improving the light transmittance, generally increasing it to about 91%-92% at most. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method and terminal for improving the light transmittance of microcrystalline glass, in view of the above-mentioned defects of the prior art.

[0007] To achieve the above objectives, the present invention provides a method for improving the light transmittance of glass-ceramics, the method comprising the following steps:

[0008] Step S1, prepare a sodium aluminum silicon oxide mixture, which, by molar percentage, comprises the following components:

[0009] Na2O: 10%-30%;

[0010] Al2O3: 10-30%;

[0011] SiO2: 50%-70%;

[0012] Step S2: Prepare the molten salt bath required for each step of the chemical strengthening process;

[0013] Step S3: Add the sodium aluminum silicon oxide mixture to the molten salt bath of the last step and mix well;

[0014] Step S4: Immerse one or more pieces of microcrystalline glass in the molten salt bath corresponding to each step in sequence for chemical strengthening.

[0015] Preferably, the mass of the sodium aluminum silicon oxide mixture to be prepared is determined according to the size of the glass-ceramic, such that the pH value of the salt bath formed by the molten salt and the sodium aluminum silicon oxide mixture is ≥8.

[0016] Preferably, the chemical strengthening is a two-step strengthening process. In the first step, molten salt is prepared using NaNO3, and the strengthening time is 1-5 hours. In the second step, a salt bath is formed by mixing KNO3 and sodium aluminum silicon oxide, and the strengthening time is 5-90 minutes.

[0017] Preferably, the chemical strengthening is a two-step strengthening process. In the first step, molten salt is prepared using NaNO3, and the strengthening time is 1-5 hours. In the second step, a molten salt mixture is prepared using KNO3 and NaNO3 in a mass ratio of 3:7. The molten salt mixture is then mixed with a sodium aluminum silicon oxide mixture to form a salt bath, and the strengthening time is 10-90 minutes.

[0018] Preferably, the chemical strengthening is a one-step strengthening, in which a molten salt mixture is prepared using KNO3 and NaNO3 in a mass ratio of 3:7, and then the molten salt mixture is mixed with a sodium aluminum silicon oxide mixture to form a salt bath, and the strengthening time is 4-9 hours.

[0019] Preferably, the temperature for chemical strengthening is 350°C to 450°C.

[0020] The present invention also provides a terminal, the terminal including a housing assembled on the outside of the terminal and a circuit board located inside the housing, the housing being made of microcrystalline glass processed by the method described above.

[0021] Preferably, the housing includes a display screen cover assembled on the front side of the terminal, the display screen cover being made of microcrystalline glass processed by the method described above.

[0022] Preferably, the housing includes a rear cover assembled on the rear side of the terminal, the rear cover being made of microcrystalline glass processed by the method described above.

[0023] Preferably, the terminal further includes a camera assembly located inside the housing, the housing including a camera protective cover, the camera protective cover covering the camera assembly, and the camera protective cover and camera lens being made of microcrystalline glass processed by the method described above.

[0024] The technical solution of this invention involves adding a mixture of sodium aluminum silicon oxide to a conventional chemically strengthened salt bath. The sodium aluminum silicon oxide reacts with the microcrystalline and glassy phases on the surface of the glass-ceramic glass, changing the ratio of the glassy and microcrystalline phases. This forms a refractive index gradient layer on the glass surface from the outside in, reducing light reflection through light interference. Simultaneously, ion exchange occurs between the glass-ceramic glass and the salt bath, creating a stress layer on the surface of the glass-ceramic glass. This effectively improves light transmittance while enhancing the glass strength. The chemical strengthening is carried out in a strengthening furnace, resulting in a higher product yield compared to vacuum coating. Attached Figure Description

[0025] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0026] Figure 1 This is a schematic diagram illustrating the steps of a method for improving the light transmittance of microcrystalline glass according to an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The general idea of ​​this invention is to add a mixture of sodium aluminum silicon oxide to a conventional chemically strengthened salt bath. The sodium aluminum silicon oxide reacts with the microcrystalline phase and glass phase on the surface of the glass-ceramic glass, changing the ratio of the glass phase to the microcrystalline phase. This forms a refractive index gradient layer on the glass surface from the outside to the inside. At the same time, the glass-ceramic glass undergoes ion exchange with the salt bath, generating a stress layer on the surface of the glass-ceramic glass. This effectively improves the light transmittance while enhancing the strength of the glass.

[0029] The embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. It should be understood that the embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0030] This invention is applicable to improving the light transmittance of glass-ceramics, and the improved glass-ceramics are particularly suitable for equipment and fields with high light transmittance requirements.

[0031] Light transmittance refers to the ability of light to pass through a medium; it is the percentage of luminous flux passing through a transparent or translucent body relative to the incident luminous flux. Transmittance is expressed as a percentage and ranges from 0% to 100%. The magnitude of light transmittance directly affects the visual effect of optical products. For glass-ceramics, the luminous flux transmitted through the glass-ceramic is the incident luminous flux minus the luminous flux reflected, scattered, and absorbed. The scattered and absorbed luminous flux is relatively small and can be ignored; therefore, reducing the reflected luminous flux increases the luminous flux transmitted through the glass-ceramic. The reflected luminous flux is characterized by the reflectivity of the glass, and the transmitted luminous flux is characterized by the transmittance; reflectivity + transmittance ≈ 100%.

[0032] The light transmittance mentioned in this invention refers to the transmittance of visible light of different wavelengths through the microcrystalline glass.

[0033] like Figure 1 As shown, this embodiment of the invention provides a method for improving the light transmittance of microcrystalline glass, the method comprising the following steps:

[0034] Step S1, prepare a sodium aluminum silicon oxide mixture, which, by molar percentage, comprises the following components:

[0035] Na2O: 10%-30%;

[0036] Al2O3: 10-30%;

[0037] SiO2: 50%-70%.

[0038] In this embodiment of the invention, the sodium aluminum silicon oxide mixture is used because sodium aluminum silicon oxide is a major component of glass-ceramics, is alkaline after melting, and is low in cost, chemically stable, and convenient to store, transport, and use after melting. In this embodiment of the invention, the molar percentages of each component in the sodium aluminum silicon oxide mixture are: Na₂O: 20%, Al₂O₃: 20%, SiO₂: 60%.

[0039] The mass of the sodium aluminum silicon oxide mixture to be prepared is determined according to the size of the glass-ceramic glass, such that the pH value of the salt bath formed by the molten salt and the sodium aluminum silicon oxide mixture is ≥8.

[0040] In this embodiment of the invention, the dimensions of the microcrystalline glass are: length 160–180 mm, width 60–75 mm, and thickness 0.45–0.7 mm. The mass of the sodium aluminum silicon oxide mixture corresponding to each piece of microcrystalline glass is 5–20 g. When applied to microcrystalline glass of other sizes, the mass of the sodium aluminum silicon oxide mixture is adjusted according to the size ratio of the microcrystalline glass. Experiments show that the mass ratio of the sodium aluminum silicon oxide mixture is more suitable when the pH value of the salt bath formed by the molten salt and the sodium aluminum silicon oxide mixture is ≥8. Preferably, the pH value of the salt bath formed by the molten salt and the sodium aluminum silicon oxide mixture is between 8 and 9.

[0041] Specifically, in this embodiment of the invention, the preparation method of the sodium aluminum silicon oxide mixture is similar to that of glass, involving the mixing of Na2O and Al2O. 3、 SiO2 is mixed evenly in proportion. Depending on the melting difficulty of each component, it is melted in an electric furnace or gas furnace. After stirring to make it uniform, it is cooled to an appropriate temperature and poured into a mold. It is then slowly cooled, and the solid material formed after cooling is broken into small particles for easy use and weighing.

[0042] Step S2: Prepare the molten salt bath required for each step of the chemical strengthening process;

[0043] The aforementioned chemical strengthening, also known as "ion exchange," typically uses a salt bath containing monovalent alkali metal ions. The ion exchange process involves immersing the glass-ceramic in a single salt bath or sequentially in multiple salt baths. During ion exchange, smaller-radius metal ions in the glass-ceramic are replaced by larger-radius metal ions with the same valence state nearby. This "squeezing effect" creates a compressive stress layer on the surface, forming an ion exchange layer of a certain depth. Ion exchange can achieve a higher ion exchange layer depth and greater surface compressive stress, thereby enhancing the glass's strength and effectively improving its drop resistance.

[0044] Step S3: Add the sodium aluminum silicon oxide mixture to the molten salt bath of the last step and mix well;

[0045] Step S4: Immerse one or more pieces of microcrystalline glass in the molten salt bath corresponding to each step in sequence for chemical strengthening.

[0046] When strengthening multiple glass-ceramic sheets, care must be taken to ensure that the glass-ceramic sheets do not overlap and that sufficient space is maintained so that each surface of the glass-ceramic can be adequately chemically strengthened.

[0047] In some embodiments, the chemical strengthening is a two-step strengthening process: first, molten salt is prepared using NaNO3, and the strengthening time is 1-5 hours; second, a salt bath is formed by mixing KNO3 and molten sodium aluminum silicon oxide, and the strengthening time is 5-90 minutes.

[0048] Ion exchange can improve the light transmittance of glass-ceramics. Taking the two-step strengthening process mentioned above as an example, in the first step, lithium ions in the glass are exchanged for sodium ions in the molten salt, resulting in a decrease in refractive index; in the second step, sodium ions in the glass are exchanged for potassium ions in the molten salt, resulting in an increase in refractive index. By controlling the exchange amounts of lithium, sodium, and potassium, ion exchange layers with different refractive indices can be obtained. The ion exchange layers reduce light reflection, thus improving light transmittance. However, the refractive index of the ion exchange layer obtained through ion exchange is not significantly different from that of the intermediate layer in the glass-ceramic bulk, so the improvement effect on light transmittance is not obvious.

[0049] In this embodiment of the invention, a mixture of sodium aluminum silicon oxide is added to a conventional chemically strengthened salt bath. The sodium aluminum silicon oxide, after melting at high temperatures, is alkaline and reacts with the microcrystalline and glassy phases on the surface of the glass-ceramic. Under the influence of the sodium aluminum silicon oxide, both phases decompose. The microcrystalline phase exhibits high stability, while the glassy phase has poor stability, and its decomposition rate is faster than that of the microcrystalline phase. Ultimately, the network structure of the glass-ceramic surface becomes looser, and the ratio of the glassy phase to the microcrystalline phase changes. This accelerates the formation of a low-refractive-index layer, creating a gradient layer with a large refractive index gradient from the outside to the inside of the glass surface. This gradient layer can reduce the amount of light reflection through light interference, thereby effectively improving light transmittance.

[0050] In this embodiment of the invention, the thickness of the effective refractive index gradient layer is 50nm-500nm. Different process parameters result in different levels of light transmittance. The light transmittance of the microcrystalline glass processed by the process of this invention can reach 92%-98%, and the product yield is 99.5%.

[0051] Tables 1-2 show experimental data obtained from the chemical strengthening of microcrystalline glass with dimensions of 160-180 mm in length, 60-75 mm in width, and 0.45-0.7 mm in thickness using the two-step chemical strengthening method described above. Before chemical strengthening, the reflectivity of the microcrystalline glass was 8-9%, and the light transmittance was 90-91%. The mass of the sodium aluminum silicon oxide mixture used in each example was different. In Table 1, the second strengthening time was 60 minutes, while in Table 2, the second strengthening time was 20 minutes. The masses of the sodium aluminum silicon oxide mixture in Examples 1-5 of Table 1 and the masses of the sodium aluminum silicon oxide mixture in Examples 6-10 of Table 2 correspond sequentially. The light transmittance data were measured using a spectrometer, with a wavelength range of 380 nm-1000 nm.

[0052] Table 1

[0053]

[0054]

[0055] Table 2

[0056] Reflectance of light at a wavelength of 550nm (%) 7.63 8.4 8.06 8.14 8.41 Transmittance of light at 550nm wavelength (%) 92.323 91.61 91.572 91.944 91.723 Transmittance of light at 380nm wavelength (%) 91.585 90.447 90.119 90.734 90.927 Transmittance of light at 465nm wavelength (%) 92.351 91.396 91.28 91.598 91.651 Transmittance of light at 635nm wavelength (%) 92.501 91.751 91.663 91.859 91.914 Transmittance of light at 720nm wavelength (%) 92.551 91.908 91.835 92.132 91.986 Transmittance of light at 860nm wavelength (%) 92.326 91.86 91.929 92.003 91.878 Transmittance of light at a wavelength of 1000nm (%) 92.04 91.811 91.806 91.88 91.779

[0057] The experimental data in Table 1-2 show that after the two-step chemical strengthening process, the reflectivity of the glass-ceramic decreased compared to before strengthening, with the effect being particularly pronounced when the second strengthening time was 60 minutes. Corresponding to the decrease in reflectivity, the light transmittance of the glass-ceramic increased accordingly. In practical applications, repeated experiments should be conducted based on the target light transmittance to determine the appropriate strengthening time.

[0058] In some embodiments, the chemical strengthening is a two-step process. First, molten salt is prepared using NaNO3, with a strengthening time of 1-5 hours. Second, a molten salt mixture is prepared using KNO3 and NaNO3 in a 3:7 mass ratio, and then this molten salt mixture is mixed with a sodium aluminum silicon oxide mixture to form a salt bath, with a strengthening time of 10-90 minutes. This method is similar to the first embodiment, except that the preparation of the chemically strengthened salt bath differs. The specific strengthening time depends on factors such as the size and quantity of the glass-ceramic, the desired intensity and light transmittance parameters, and the mass of the sodium aluminum silicon oxide mixture.

[0059] In some embodiments, the chemical strengthening is a one-step strengthening process. A molten salt mixture is prepared using KNO3 and NaNO3 in a 3:7 mass ratio. This molten salt mixture is then mixed with a sodium aluminum silicon oxide mixture to form a salt bath, and the strengthening time is 4-9 hours. This method requires only the preparation of one salt bath, eliminating the need for the transfer and washing of the glass-ceramic between the two strengthening steps, thus simplifying the operation. The specific strengthening time depends on factors such as the size and quantity of the glass-ceramic, the desired intensity and light transmittance parameters, and the mass of the sodium aluminum silicon oxide mixture.

[0060] In addition to the three implementation methods described above, other chemical strengthening methods in the prior art can also be used, or other salts can be used to replace KNO3 and NaNO3. Similar to the implementation methods described above, a mixture of sodium aluminum silicon oxides can be added to the salt bath in the final chemical strengthening step to participate in the chemical strengthening.

[0061] The chemical strengthening temperature is 350℃~450℃. Chemical strengthening is carried out in a strengthening furnace. At the high temperature of 350℃~450℃, the solid sodium aluminum silicon oxide mixture reacts more rapidly with the glass-ceramic, thereby improving the strengthening efficiency.

[0062] The principle behind this invention is that the crystalline phase and the glass phase in glass-ceramics have different stability. For glass-ceramics containing multiple crystalline phases, the stability of each phase typically varies, resulting in a greater gradient of stability differences compared to single-phase glass-ceramics, leading to a more significant improvement in light transmittance. Therefore, compared to existing technologies that adjust light transmittance by carefully designing the composition and proportion of each component in the glass-ceramic, this invention does not have special requirements for the composition of the glass-ceramic, making it highly versatile. This invention can process multiple glass sheets simultaneously, and compared to improving light transmittance through coating layers, it offers greater operability, efficiency, and yield.

[0063] This invention also discloses a terminal, which includes a housing assembled on the outside of the terminal and a circuit board located inside the housing. The housing is made of microcrystalline glass processed by the method described above.

[0064] The terminals include, but are not limited to, electronic devices such as mobile phones and tablets.

[0065] In some embodiments, the housing includes a display cover assembled on the front side of the terminal, the display cover being made of microcrystalline glass processed as described above.

[0066] In some embodiments, the housing includes a rear cover assembled on the rear side of the terminal, the rear cover being made of microcrystalline glass processed as described above.

[0067] The microcrystalline glass processed by the method described in this invention has high strength and excellent drop resistance, and therefore can be used for the back cover of a terminal.

[0068] In some embodiments, the terminal further includes a camera assembly located inside the housing, the housing including a camera protective cover covering the camera assembly, the camera protective cover and the camera lens being made of microcrystalline glass processed by the method described above.

[0069] The microcrystalline glass processed by the method described in this invention has high light transmittance, which can meet the optical display requirements of display screen covers, camera protective covers and camera lenses, and therefore can be used for display screen covers, camera protective covers and camera lenses in terminals.

[0070] The technical solution of this invention involves adding a molten sodium aluminum silicon oxide mixture to a conventional chemically strengthened salt bath. The sodium aluminum silicon oxide reacts with the microcrystalline and glassy phases on the surface of the glass-ceramic glass, altering the ratio of the glassy to the microcrystalline phases. This creates a refractive index gradient layer on the glass surface from the outside in, reducing light reflection through interference. Simultaneously, ion exchange occurs between the glass-ceramic glass and the salt bath, generating a stress layer on the surface of the glass-ceramic glass. This effectively improves light transmittance while enhancing the glass's strength. This invention can process multiple glass sheets simultaneously, has no special requirements for the composition of the glass-ceramic glass, does not require a vacuum environment, and offers advantages such as good light transmittance enhancement, low cost, high operability, higher efficiency and product yield, and wide applicability.

[0071] The above are merely specific embodiments of the present invention and should not be construed as limiting the scope of the present invention. Equivalent variations made by those skilled in the art based on this invention, as well as changes well-known to those skilled in the art, should still fall within the scope of the present invention.

Claims

1. A method for improving the light transmittance of glass-ceramics, characterized in that, The method includes the following steps: Step S1, prepare a sodium aluminum silicon oxide mixture, which, by molar percentage, comprises the following components: Na2O: 10%-30%; Al2O3: 10-30%; SiO2: 50%-70%; Step S2: Prepare the molten salt bath required for each step of the chemical strengthening process; Step S3: Add the sodium aluminum silicon oxide mixture to the molten salt bath of the last step and mix well; determine the mass of the sodium aluminum silicon oxide mixture to be prepared according to the size of the microcrystalline glass, so that the pH value of the salt bath formed by the molten salt and the sodium aluminum silicon oxide mixture is ≥8. Step S4: Immerse one or more pieces of microcrystalline glass in the molten salt bath corresponding to each step in sequence for chemical strengthening. The sodium aluminum silicon oxide mixture reacts with the microcrystalline phase and glass phase on the surface of the glass-ceramic glass, changing the ratio of the glass phase and the microcrystalline phase, and forming a refractive index gradient layer on the glass surface from the outside to the inside.

2. The method for improving the light transmittance of microcrystalline glass according to claim 1, characterized in that, The chemical strengthening is a two-step process. In the first step, molten salt is prepared using NaNO3, and the strengthening time is 1-5 hours. In the second step, a salt bath is formed by mixing KNO3 and sodium aluminum silicon oxide, and the strengthening time is 5-90 minutes.

3. The method for improving the light transmittance of microcrystalline glass according to claim 1, characterized in that, The chemical strengthening is a two-step strengthening process. In the first step, molten salt is prepared using NaNO3, and the strengthening time is 1-5 hours. In the second step, a molten salt mixture is prepared using KNO3 and NaNO3 in a mass ratio of 3:

7. The molten salt mixture is then mixed with a sodium aluminum silicon oxide mixture to form a salt bath, and the strengthening time is 10-90 minutes.

4. The method for improving the light transmittance of glass-ceramics according to claim 1, characterized in that, The chemical strengthening is a one-step strengthening process, in which a molten salt mixture is prepared using KNO3 and NaNO3 in a mass ratio of 3:7, and then the molten salt mixture is mixed with a sodium aluminum silicon oxide mixture to form a salt bath. The strengthening time is 4-9 hours.

5. The method for improving the light transmittance of glass-ceramics according to claim 1, characterized in that, The temperature for chemical strengthening is 350℃~450℃.

6. A terminal, characterized in that, The terminal includes a housing assembled on the outside of the terminal and a circuit board located inside the housing, the housing being made of microcrystalline glass processed by the method of any one of claims 1-5.

7. The terminal according to claim 6, characterized in that, The housing includes a display cover assembled on the front side of the terminal, the display cover being made of microcrystalline glass processed by the method described in any one of claims 1-5.

8. The terminal according to claim 6, characterized in that, The housing includes a rear cover assembled on the rear side of the terminal, the rear cover being made of microcrystalline glass processed by the method described in any one of claims 1-5.

9. The terminal according to claim 6, characterized in that, The terminal further includes a camera assembly located inside the housing. The housing includes a camera protective cover, which covers the camera assembly. The camera protective cover and the camera lens are made of microcrystalline glass processed by the method described in any one of claims 1-5.

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